1. Field of the Invention
The invention relates generally to the subject of communication with submarines or other submerged objects, particularly through modulated light beams.
2. Description of the Prior Art
In the prior art the problem of communicating with submarines at sea has received much attention. Obviously, submarines can surface and communicate by radio in the same manner as surface vessel communication is commonly conducted. In naval operational situations however, the missions assigned to submarines are considerably different from those undertaken by surface vessels. It is a great disadvantage if a submarine is required to surface in order to conduct communications, because of its great vulnerability when surfaced, and also because communications are thereby precluding during periods when surfacing is not permissible.
Radio communication systems have been devised permitting some degree of communication with submerged submarines, however, these are sharply limited in their application because of attenuation problems and also because they provide a means whereby hostile forces may locate and identify them when transmissions are made from the submarine.
The use of surface buoys connected by electrical cable to a submarine permit the maintenance of relatively safe depth, but are also suspectible to surface detection.
Communication with a friendly aircraft over the area occupied by a submerged submarine or with orbiting satellites is possible using the highly directive properties of modulated laser light beams. The energy of such beams does not tend to be dispersed beyond the immediate location, thereby readily improving the security of the communication link. A laser beam (the preferred type of optical communication medium) is also known for its capability for penetrating at least some depth of sea water, although there are situations in which submarine operations are conducted well below the levels at which even the most powerful laser beam could be expected to penetrate.
The manner in which the present invention deals with the problems of the prior art to provide a unique arrangement for submarine communication, which is both highly secure, from the point of view of integrity of the communication link, and does not provide a substantial opportunity for hostile identification of a submarine and its location, will be seen as this description proceeds.